Subchondral changes in transient osteoporosis of the hip

Objective. To review the subchondral changes on MR imaging in transient osteoporosis of the hip (TOH) and to consider the pathophysiology. Design and patients. MR images of 12 hips of 11 consecutive patients with TOH were retrospectively studied. The diagnoses of TOH were confirmed on the basis of previously published criteria, including decreased bone density of the femoral head and/or neck on radiographs, bone marrow edema (BME) pattern on MR images, spontaneous resolution of the symptoms and a return to normal radiodensity. Results. All 12 hips showed a BME pattern in the femoral head and/or neck. Linear patterns of very low signal intensity were identified on T1-weighted images in the subchondral area within the diffuse low signal intensity area in all 12 hips. On T2-weighted images, a low signal intensity line was observed in the corresponding area in eight hips only. These linear patterns were thought to represent subchondral fracture lines. Conclusions. The presence of a subchondral fracture may be important when considering the pathophysiology of TOH. Received: 5 April 2000 Revision requested: 11 July 2000 Revision received: 22 January 2001 Accepted: 29 January 2001     

A subchondral fracture in transient osteoporosis of the hip

Although subchondral changes are reported to be associated with transient osteoporosis of the hip (TOH), the etiology of this disorder is unknown.In this paper, we describe a 45-year-old man with TOH who underwent both MRI and CT examinations. Plain radiographs obtained 2 months after the onset of hip pain showed a focal loss of radiodensity in the left femoral head. MRI revealed a bone marrow edema pattern in the left femoral head and neck with an associated subchondral serpiginous low signal intensity line on the T1-weighted images. A CT scan showed a subchondral fracture in the corresponding area. The hip pain and imaging abnormalities resolved spontaneously following conservative treatment.This case study demonstrated that a subchondral fracture of the femoral head was associated with TOH using MRI and CT examinations, and suggests that the presence of a subchondral fracture may be important for the pathophysiology of TOH.     

股骨头缺血坏死与伴有骨髓水肿的一过性骨质疏松的MRI表现及其研究进展

股骨头由于其血供特点,很易于发生缺血坏死。股骨头缺血性坏死是引起髋部疼痛的常见病,是渐进性疾病,主要累及年轻人,影像检查的目的是对其进行早期诊断,评价其坏死程度。一过性骨质疏松属自限性疾病,一过性疾病。骨髓水肿是以上两种疾病的主要MRI表现,笔者就有关问题综述如下。     

Bone marrow edema of the femoral head and transient osteoporosis of the hip

The current article of this issue aims at defining the generic term of bone marrow edema of the femoral head as seen at MR imaging. It must be kept in mind that this syndrome should be regarded, not as a specific diagnosis, but rather as a sign of an ongoing abnormal process that involves the femoral head and/or the hip joint. We aim at emphasizing the role of the radiologists in making a specific diagnosis, starting from a non-specific finding on T1-weighted images and by focusing on ancillary findings on T2-weighted SE or fat-saturated proton-density weighted MR images.     

Intra-articular regional migratory osteoporosis of the knee

We report a case of lntra-articular regional migratory osteoporosis of the knee in a 53-year-old man. The case demonstrates an unusual pattern of migration of the marrow edema within the knee joint. This phenomenon has received scant attention in the radiological literature. Received: 9 July 1999 Revision requested: 24 August 1999 Revision received: 6 October 1999 Accepted: 8 October 1999     

MR imaging findings in transient osteoporosis of the hip

Purpose: The authors sought to describe the magnetic resonance (MR) imaging findings including perfusion imaging, in association with the course of acute bone marrow oedema syndrome (aBMEs), in a group of patients with acute hip pain and a final diagnosis of transient osteoporosis of the hip (TOH). Materials and methods: From 217 patients referred with a probable diagnosis of avascular necrosis (AVN) of the femoral head, we identified 42 patients who had clinical and radiographic findings not relevant to AVN. MR imaging examinations were performed on a 1.0T scanner. Perfusion imaging was performed in 20 patients. The bone marrow oedema (BME) was classified in four stages. In addition, the presence or absence of oedema in the subchondral area and the presence of other subchondral lesions were recorded. Acetabular bone marrow was also assessed for the presence of oedema. The quantitative measurements included: maximum size of the effusion, percentage of enhancement (PE) and time of peak enhancement of abnormal marrow compared to the first pass, on the perfusion images. Results: Osteopenia was present on plain radiographs in 87% of cases. The most common pattern of BME was extending to the femoral head and neck. Acetabulum was involved in 16.6%. In 22.6% the BME spared the subchondral region of the femoral head. There were two cases (4.7%) with subchondral changes. A joint effusion was noted in 33 of the 42 patients. On perfusion imaging, a delayed peak enhancement was noted in 20 patients between 40 and 65 s after the first pass of contrast. No patient had any evidence of femoral head collapse or change in sphericity on follow-up MRI. None of the patients developed avascular necrosis in a time frame of 18 months from the onset of the acute hip pain. Conclusion: The aBMEs MR imaging pattern varies and is most commonly appearing on X-rays as osteopenia. Absence of subcondral lesions, delayed peak enhancement of the abnormal marrow on perfusion images, and sparing of subchondral zone from marrow oedema are MR imaging findings highly correlated to TOH.     

暂时性骨质疏松症的MRI表现

目的:探讨暂时性骨质疏松症的MRI表现。方法:对经临床证实的10例暂时性骨质疏松症(TOH)患者的临床及影像学资料进行回顾性分析。10例患者均行MRI平扫,其中5例行MRI增强扫描,4例行CT扫描。10例中男7例,女3例,年龄为25～40岁。结果:10例TOH中,双侧髋关节同时受累2例,单侧受累8例,主要MRI表现为弥漫性骨髓水肿,累及股骨头、颈及转子间,股骨头形态完整,1例可见软骨下应力性骨折,所有病例均无股骨头软骨下骨质缺损;关节囊肿胀和关节积液8髋;MRI增强扫描示病变区呈明显均匀强化。主要CT表现为股骨头骨密度弥漫性减低,骨皮质变薄。治疗5～11个月后患者疼痛症状消失,股骨内MRI信号恢复正常。结论:CT上表现为弥漫性骨质疏松、MRI表现为弥漫性骨髓水肿、缺乏软骨下骨质病变以及均匀一致强化是TOH性特征的影像学表现。     

Magnetic resonance imaging criteria of successful core decompression in avascular necrosis of the hip

To identify imaging criteria that determine the outcome of core decompression (CD) in femoral-head avascular necrosis (AVN). Radiographs and magnetic resonance imaging (MRI) of 65 hips with early stage AVN treated by core decompression between January 1990 and December 2000 for AVN were reviewed. All hips were categorized into two groups according to the result of CD using total hip arthroplasty (THA) as an end point. Hips that had no THA at follow-up were allocated to group I; those treated with a THA were allocated to group II. CD results were calculated for each group using THA as an end point. The parameters analyzed were the presence or absence of edema associated with the double-line sign on the preoperative MRI, the type of epiphyseal scar (ES) according to Jing, and the type of necrosis according to Mitchell. On follow-up, 45 hips had no THA (group I); 20 patients had a THA (group II). Patients with a radiographic crescent sign and those with edema associated with the double-line sign progressed to THA significantly more frequently. The extent of the necrosis had less discriminatory effect between the two groups. ES and necrotic tissue types had no prognostic value. In regard to the success of CD, it is important to differentiate on MRI between a double line sign plus bone marrow edema and a double-line sign only.     

Partial transient osteoporosis of the hand

Objective. To describe the radiographic and scintigraphic findings of partial transient osteoporosis (PTO) of the hand. To discuss the relationship of PTO and other localized demineralizing diseases. Design and patients. Three patients with PTO that affected two or three digits of the hand are reported. Two patients were middle-aged women and the third was a young man. All presented with a history of trauma to the hand. All patients experienced localized burning pain, swelling and vasomotor changes including redness of the skin, hyperhidrosis and signs of vasomotor instability of the involved fingers. Plain radiography and bone scanning were used in the diagnosis and follow-up of these cases. Results. All patients had a radial distribution of the osteoporosis that involved adjacent rays. In all patients two rays were involved. The radiographic changes manifested as minimal patchy osteoporosis involving the cortical, cancellous, subarticular and subperiosteal bone with no articular involvement. The increased uptake on scintigraphy coincided with the radial distribution of the osteoporosis. All patients improved on physical therapy and were symptom-free approximately 6 months after the initial injury. These patients were followed up for more than 2 years. Conclusion. PTO of the hand is an uncommon disease with typical clinical and radiographic findings. Bone scintigraphy confirms the partial involvement of the hand. Received: 27 February 1998 Revision requested: 18 June 1998 Revision received: 4 March 1999 Accepted: 15 April 1999     

Partial transient osteoporosis

Regional transient osteoporosis (algodystrophie décalcifiante) has been recognised as a clinical and radiological syndrome in a number of reports published between 1947 and 1968 [16, 17, 23, 24, 11]. The condition is characterised clinically by the development of severe and often incapacitating pain around a major joint, usually the ankle, the knee, or the hip in middle-aged and elderly adults. Haematological and biochemical studies are essentially unrewarding. Radiological examination initially reveals no abnormality, but one or two months after the onset of symptoms widespread osteoporosis is demonstrated around the affected joint. The clinical symptoms resolve spontaneously within approximately four to ten months with subsequent remineralisation of the osteoporotic areas. In about a third to a quarter of cases the cause is unknown (idiopathic form). In the remainder, a history of minor or major trauma, including surgery, is elicited in more than half the patients, suggesting the entity to be analogous to Sudeck's atrophy. Other apparent precipitating factors include neuralgia, herpes zoster, hemiplegia, and vascular disturbances. These secondary or reflex forms do not differ from the idiopathic form. Transient osteoporosis of the hip or knee is more commonly idiopathic, whereas involvement of the ankle or foot is often secondary to trauma. In most instances the osteoporosis spread ultimately to produce the classical pattern of diffuse peri-articular demineralisation, especially around the weight-bearing joints of the lower limb.Two different radiological manifestations of partial transient osteoporosis have been observed. (1) The radial form, which involves only one or two rays of the hand or foot (two cases). (2) The zonal form in which the area of demineralisation is confined initially to such structures as one femoral condyle or one quadrant of a femoral head (six cases). These abnormalities developed one or two months after the onset of symptoms. Diagnostic detail was improved by tomography. Scintigraphy revealed an increased uptake of technetium-99m, not only in the demineralised area of bone but also—to a lesser degree—in the surrounding bone structures as well. Biopsy, performed in two cases, demonstrated diffuse osteoporosis alone. All the patients reported in this series became asymptomatic in approximately six months.     

MR findings of necrotic lesions and the extralesional area of osteonecrosis of the femoral head

Objective. To investigate the MR findings of necrotic lesions and the extralesional area of osteonecrosis of the femoral head (ONFH) for each of the radiological stages. Design and patients. Forty-nine hips in 29 patients (15 female, 14 male; mean age 38 years, range 17–59 years) were imaged using a 1.0-T superconducting magnet. T2-weighted spin echo pulse sequences (T2WI), spoiled gradient recalled echo pulse sequences (SPGR) and fat suppression SPGR (FS-SPGR), followed by Gd-DTPA enhanced fat suppression SPGR (Gd-FS-SPGR), were all obtained with the aid of a TORSO surface coil. Results and conclusions. While a normal fat intensity area with a low-intensity band on SPGR (band pattern) was seen in 16 of 16 stage 1 (100%), nine of 11 stage 2 (82%), four of 17 stage 3 (24%), and none of five stage 4 hips, all hips showed peripheral rim enhancement on Gd-FS-SPGR (100%). This enhancement band on Gd-FS-SPGR corresponded to histological findings of necrotic trabecular bone, repaired marrow, and fibrous reparative tissue. Bone marrow edema was also clearly demonstrated as a diffuse, high-intensity area outside this enhancement band on Gd-FS-SPGR in two stage 2 (18%), 12 stage 3 (71%), and one stage 4 hip (20%). In cases at stage 2 or more advanced stages with homogeneous or inhomogeneous low intensity on nonenhanced MRI, the reparative process both inside and outside the necrotic lesion, including bone marrow edema, was detected clearly on contrast- enhanced MRI. Received: 3 August 1999 Revision requested: 28 September 1999 Revision received: 11 November 1999 Accepted: 2 December 1999     

Ischemic necrosis of the entire femoral head and rapidly destructive hip disease: potential causative relationship

 Objective. Rapidly destructive hip disease (RDHD) is an uncommon disorder of the hip that has been considered a disease of unknown cause and distinct from ischemic necrosis of the femoral head. The objective of this study was to investigate ischemic necrosis of the femoral head as one potential cause of RDHD. Design and patients. In 600 patients who underwent MR imaging of the hip, 20 cases of ischemic necrosis involving the entire femoral head in 18 patients (3%) were retrospectively studied with routine radiography and MR imaging. All patients had surgically confirmed ischemic necrosis of the femoral head. Results and conclusions. All patients showed rapid destruction of the femoral head on routine radiography and MR imaging as compared with the gradual onset of clinical symptoms. Plain radiographs showed several bone fragments at the inferomedial aspect of the femoral head (75%), acetabular erosions (55%), eccentric depression at the lateral articular surface of the femoral head conforming to the adjacent acetabulum (35%), and mild osteoarthritis (15%). Bone sclerosis was often present at sites of impaction between the femoral head and the acetabulum. MR imaging showed marked distention of the joint capsule in all cases. In 14 of 20 cases, the contents of the joint space showed predominantly low or intermediate signal intensity on T1- and T2-weighted images. Ischemic necrosis involving the entire femoral head may represent one of the causes of RDHD.     

Regional migratory osteoporosis in the knee: MRI findings in 22 patients and review of the literature

OBJECTIVE: Acute non-traumatic bone marrow edema (BME) in the knee is a common clinical problem. The aim of the present study is to present the MR imaging findings of the uncommon transient migratory pattern of this syndrome. MATERIALS AND METHODS: Twenty-two patients (21 men, 1 woman, age range 35-73 years, mean 49.4+/-7.6) who presented with pain in the knee joint (ranging from 2 weeks to 6 months) and BME in the MR imaging examination, were included in the study. In all cases, the knee joint BME was either preceded or followed by another site of BME in the same or another joint. All patients were studied with plain X-rays and MR imaging at presentation and with MR imaging after resolution of symptoms. RESULTS: The eight patients with initial involvement in the knee showed migration either intra-articularly (5), or/and in the contralateral knee (2) and only 1 case showed migration to the ipsilateral hip joint. In two patients the BME shifted from the hip first to the foot and then to the knee. The median migration period was 4 months for the second involvement in all patients and 3 months for the third involvement (10 patients). CONCLUSIONS: The present study reports the largest series of patients with regional migratory osteoporosis involving the knee. In most of the cases, shifting of BME remains in the joint or moves to the contralateral knee. In only one case the BME shifted from the knee elsewhere. All lesions were transient.     

Bone marrow edema syndrome

Bone marrow edema syndrome (BMES) refers to transient clinical conditions with unknown pathogenic mechanism, such as transient osteoporosis of the hip (TOH), regional migratory osteoporosis (RMO), and reflex sympathetic dystrophy (RSD). BMES is primarily characterized by bone marrow edema (BME) pattern. The disease mainly affects the hip, the knee, and the ankle of middle-aged males. Many hypotheses have been proposed to explain the pathogenesis of the disease. Unfortunately, the etiology of BMES remains obscure. The hallmark that separates BMES from other conditions presented with BME pattern is its self-limited nature. Laboratory tests usually do not contribute to the diagnosis. Histological examination of the lesion is unnecessary. Plain radiographs may reveal regional osseous demineralization. Magnetic resonance imaging is mainly used for the early diagnosis and monitoring the progression of the disease. Early differentiation from other aggressive conditions with long-term sequelae is essential in order to avoid unnecessary treatment. Clinical entities, such as TOH, RMO, and RSD are spontaneously resolving, and surgical treatment is not needed. On the other hand, early differential diagnosis and surgical treatment in case of osteonecrosis is of crucial importance.     

Shifting bone marrow edema of the knee

Objective. The purpose of our study is to describe shifting bone marrow edema in the knee as the MR imaging feature of intra-articular regional migratory osteoporosis of the knee.Patients and methods. Five men, aged 45–73 years, were referred by orthopedic surgeons for MR imaging evaluation of knee pain, which had been present for 2 weeks to 6 months. One patient had a prior history of blunt trauma. None had risk factors for osteonecrosis. Four patients had two MR examinations and the patient with prior blunt trauma had four. Plain radiographs were obtained in all patients.Results. In all cases, a large area of marrow edema initially involved a femoral condyle, with migration of the bone marrow edema to the other femoral condyle, tibia, and/or patella occurring over a 2- to 4-month period. Adjacent soft tissue edema was present in all five patients, while none had a joint effusion. Radiographs of two patients showed generalized osteopenia.Conclusion. In the absence of acute trauma or clinical suspicion of infection, a large area of bone marrow edema without a zone of demarcation may represent intra-articular regional migratory osteoporosis. Demonstration of shifting bone marrow edema on follow-up examinations suggests this diagnosis.     

Bone scintigraphy and magnetic resonance imaging after transtrochanteric rotational osteotomy

Objective. To assess the ability of bone scintigraphy and magnetic resonance imaging (MRI) to predict the outcome of transtrochanteric rotational osteotomy (TRO) for osteonecrosis of the femoral head (ONFH). Design. This study was a prospective evaluation of imaging techniques. Patients and methods. MRI and bone scintigraphy were performed on 20 hips in 18 patients at 3 months after TRO. The radiographic findings at 3 months after TRO, and the MRI and bone scintigraphic findings, were compared with the radiographic findings at final follow-up (mean 39 months). Results and conclusions. On MRI a low-intensity area or a low-intensity band in the new weight-bearing area extending over the acetabular edge on T1-weighted images was related to the presence of collapse on the radiographs at final follow-up. In hips with an area of absent activity in the new weight-bearing surface on bone scintigraphy, collapse was seen more frequently on radiographs at final follow-up than in hips without this feature. Bone scintigraphy was no more specific than radiography in predicting the outcome after TRO. We consider MRI to be superior to bone scintigraphy in predicting the occurrence of collapse, which is one of the major short-term problems after TRO. Received: 22 July 1997 Revision requested: 2 January 1998, 12 October 1998 Revision received: 3 March 1998, 23 December 1998 Accepted: 18 January 1999     

MRI findings in regional migratory osteoporosis of the knee migrating from the femur to the tibia

Regional migratory osteoporosis (RMO) is an uncommon self-limiting disease characterized by migrating bone marrow edema and osteoporosis. RMO of the knee with intra-articular migration is very rare. In such cases, different parts of the femur are usually involved.

We report a case of intra-articular RMO of the knee migrating from the femur to the tibia—a pattern of migration that has not been previously described in the literature.     

Subchondral insufficiency fracture of the femoral head: histopathologic correlation with MRI

Objective. To correlate the magnetic resonance imaging (MRI) features with the histopathologic findings in subchondral insufficiency fracture (SIF) of the femoral head. Design and patients. This study was based on a retrospective review of the MRI features and histopathologic findings in seven patients with SIF who had had total hip replacement. Results. In all seven cases, MRI showed a bone marrow edema pattern in the femoral head, and a focal low-intensity band beneath the articular cartilage on some slices (not all) on the T1-weighted images. The shape of the low-intensity band varied: it was irregular and serpentine in four cases, well-delineated, smooth, and a mirror image to the articular surface in two cases, and parallel to the articular surface in one case. On histologic examination, the low-intensity band on MRI corresponded to a fracture line and its associated repair tissue. In all but one case, the band was not visible on T2-weighted or fat suppression images, and the proximal subchondral portion of the lesion had a homogeneous high signal intensity. This region of high signal intensity corresponded histopathologically to viable bone and marrow tissue with associated callus, edema, and vascular granulation tissue. Conclusions. SIF of the femoral head characteristically demonstrates a low-intensity band on T1-weighted images that corresponds, histopathologically, to a linear subchondral fracture and its associated repair tissue. In most cases, the subchondral portion of the lesion appears on T2-weighted images as an area of homogeneously high signal intensity. Received: 1 June 2000 Revision requested: 17 August 2000 Revision received: 11 October 2000 Accepted: 9 January 2001     

Transient osteoporosis of the knee

 The MR findings in transient osteoporosis of the knee have been described as showing a diffuse area of decreased signal intensity (relative to normal bone marrow) on T1-weighted images and increased signal intensity on T2-weighted images. We report a case of transient osteoporosis, in which MRI showed a crescentic area of abnormal signal intensity in the posterior portion of the lateral femoral condyle, which was bordered by a rim of low signal intensity, best seen on the T2-weighted images. This abnormality was shown to resolve on follow-up MR scans.     

Osteoarthritis and bone: osteologic types of osteoarthritis of the hip

To assess prognosis and indications for allografting articular surfaces, osteological examination is of increasing importance. In this study 93 femoral heads of patients with primary osteoarthritis could be differentiated into three osteologic types using histomorphometry: (1) the osteosclerotic type (77% of cases), (2) the hyperostotic type, with excessive neogenesis of bone all over the femoral head and increased formation of osteophytes (10% of cases), and (3) the osteopenic type, with decreased bone mass and features of bone remodelling, a greater occurrence of subchondral cysts, and small osteophytes (8% of cases). Radiological and clinical features to distinguish these groups are given. The consequences for pathogenesis and clinical practice are discussed.